This is an exploratory grant proposal directed at determining the function of the TWIK-2 potassium channel in vascular smooth muscle. TWIK-2 is a member of a newly discovered "Two-Pore Domain" potassium channel family (K2P). While it is expressed in a number of tissues throughout the body, TWIK-2 is particularly enriched in vascular tissue. The function of TWIK-2 in arteries or any other tissue is not known. In the spirit of the R21 Grant, this proposal involves "exploratory and developmental research" in the "early and conceptual stages" of determining the role of TWIK-2 in vascular smooth muscle. Since there are no selective activators or inhibitors for TWIK-2, we have made a TWIK-2 knockout mouse by deleting the first coding exon. This exon contains the start codon and a portion of the pore region. The goal of this proposal is to determine the role of TWIK-2 in vascular smooth muscle using our TWIK-2 knockout mouse model. Potassium channels are involved with the regulation of vascular diameter, volume regulation during osmotic stress and apoptosis, proliferation, and migration. We will address the following specific aims regarding TWIK-2 in these processes: In Specific Aim 1, we will determine if TWIK-2 is involved with the regulation of vascular diameter. In Specific Aim 2, we will determine if TWIK-2 is involved with volume regulation in vascular smooth muscle. Changes in volume as a result of K channel activation occur during apoptosis or osmotic stress. In Specific Aim 3, we will determine if TWIK-2 is involved with proliferation and/or migration of vascular smooth muscle. We will use a combination of techniques in wild type and TWIK-2 knockout mice to measure differences in function and electrical properties of vascular smooth muscle. TWIK-2 is a potentially novel and significant regulator of vascular function. Our studies should provide the essential foundation for future studies to determine the role of TWIK-2 in pathological processes. PUBLIC HEALTH RELEVANCE: Potassium channels are involved with normal physiological processes and can become dysfunctional during pathological conditions. TWIK-2, a newly discovered potassium channel, is highly expressed in arteries. The function of TWIK-2 is not presently known. The proposed research will investigate the functional role of TWIK-2 in arteries. An understanding of the role for TWIK-2 in arteries will help in understanding the regulation of blood flow and blood pressure. TWIK-2 could be a major target for therapeutic manipulation during pathological states.